Chalcedony, carnelian, onyx and cat's eyes are found in New South Wales; and it is probable that they are also to be met with in the other states, particularly in Queensland.
Well-worn pebbles of amorphous quartz (agate, chalcedony, jasper, &c.) are found in the stratified drift along the western side of the Tertiary region of the state, and from Columbus northward.
Heulandite, with thomsonite, stilbite, scolecite, calcite and chalcedony, occur as infilling minerals.
Other precious stones found are chalcedony, garnet, jacinth, amethyst, carnelian, agate, rock-crystals, &c. Amber is found at Magura in Zsepes, while fine marble quarries are found in the counties of Esztergom, Komarom, Veszprem and Szepes.
It is found in the form of oxide (silica), either anhydrous or hydrated as quartz, flint, sand, chalcedony, tridymite, opal, &c., but occurs chiefly in the form of silicates of aluminium, magnesium, iron, and the alkali and alkaline earth metals, forming the chief constituent of various clays, soils and rocks.
BLOODSTONE, the popular name of the mineral heliotrope, which is a variety of dark green chalcedony or plasma, with bright red spots, splashes and streaks.
CHALCEDONY, or Calcedony (sometimes called by old writers cassidoine), a variety of native silica, often used as an ornamental stone.
There has been some confusion between chalcedony and the ancient "carcedonia," a stone which seems to have been a carbuncle from Africa, brought by way of Carthage (Kapxn6e0v).
Our chalcedony was probably included by the ancients among the various kinds of jasper and agate, especially the varieties termed "leucachates" and "cerachates."
By modern mineralogists the name chalcedony is restricted to those kinds of silica which occur not in distinct crystals like ordinary quartz, but in concretionary, mammillated or stalactitic forms, which break with a fine splintery fracture, and display a delicate fibrous structure.
Chalcedony may be regarded as a micro-crystalline form of quartz.
A rare blue chalcedony is sometimes polished under the name of "sapphirine" - a term applied also to a distinct mineral (an aluminium-magnesium silicate) from Greenland.
Chalcedony occurs as a secondary mineral in volcanic rocks, representing usually the silica set free by the decomposition of various silicates, and deposited in cracks, forming veins, or in vesicular hollows, forming amygdales.
Its occurrence gives the name to Chalcedony Park, Arizona.
Very fine examples of stalactitic chalcedony, in whimsical forms, have been yielded by some of the Cornish copper-mines.
The surface of chalcedony is occasionally coated with a delicate bluish bloom.
Certain pseudomorphs of chalcedony after datolite, from Haytor in Devonshire, have received the name of "haytorite."
Chalcedony has been in all ages the commonest of the stones used by the gem-engraver.
The Chalcedony Cascade displays a variety of colours.
Thus in the microcrystalline chalcedony the lustre is waxy, the fracture fibrous to even, and the external form botryoidal or stalactitic flint and chert are compact and have a splintery fracture: jasper is a compact variety intermixed with much iron oxide and clay and has a dull and even fracture.
They are often intersected by dikes of chalcedony, formerly mistaken for lava.